1. Field of the Invention
This invention relates, generally, to containers for storing food and keeping the food fresh. More particularly, it relates to a resealable plastic bag of the type having a venting means for releasing air from the container after the main closure means thereof has been sealed.
2. Description of the Prior Art
It is well-known that bacteria need food, warmth and oxygen to thrive, and that food, therefore, is best stored in a cool, airless environment. Plastic bags for storing perishables provide a reasonably good means for minimizing oxygen flow to bacteria, but the oxygen trapped in the bag when the bag is sealed still enables some bacterial growth. Accordingly, a few inventors have developed resealable plastic bags having means for venting air from the bag after the primary closure means has been sealed. For example, U.S. Pat. No. 5,240,112 to Newburger (1993) discloses a resealable plastic bag having an auxiliary venting means with a structure like that of the primary sealing means. Accordingly, a sandwich is placed in the bag, the primary sealing means is closed, the venting means is opened while air is pressed out of the bag, and the venting means is then closed. The drawback of this approach is that the auxiliary venting means works with the same efficiency as the primary sealing means, i.e., the auxiliary venting means must be manually held open during the venting process, and then quickly closed manually. Air flows so quickly, however, that at least a small volume thereof is able to flow back into the bag through the auxiliary vent opening before it is closed, especially since a near vacuum exists in the bag at the moment the outward airflow ends.
There is a need, then, for an auxiliary venting means having a closure means that does not require manual operation. Specifically, there is a need for an automatic one-way valve auxiliary venting means that opens when air is flowing out of the plastic bag but which closes instantly and automatically if air attempts to flow back into the bag.
However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in this art how the needed improvements could be provided.